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Full-Text Articles in Mechanical Engineering

Impedance-Resolved Performance And Durability In Redox Flow Batteries, Alan Michael Pezeshki Dec 2016

Impedance-Resolved Performance And Durability In Redox Flow Batteries, Alan Michael Pezeshki

Doctoral Dissertations

The realization of redox flow batteries (RFBs) as a grid-scale energy solution depends on improving the performance and lifetime of the technology to decrease the high capital costs. The electrodes are a key component in the RFB; performance enhancement is often achieved through chemical or thermal treatments of commercially available porous carbon materials.

This dissertation uses impedance spectroscopy-based methods to gain insight into performance and durability in RFBs, enabling intelligent cell design. Initial work focused on understanding the impact of improved electrode and membrane properties on system performance. An accelerated stress test was then developed that can be used to ...


The Role Of Channel-Land Architecture, Diffusion Media Transport Properties, And Aging Effects On Water Transport And Storage In Polymer Electrolyte Fuel Cells, Jacob Michael Lamanna Dec 2014

The Role Of Channel-Land Architecture, Diffusion Media Transport Properties, And Aging Effects On Water Transport And Storage In Polymer Electrolyte Fuel Cells, Jacob Michael Lamanna

Doctoral Dissertations

Thermally driven transport of water vapor in polymer electrolyte fuel cells, also known as the heat-pipe effect or phase-change-induced flow, can transport several times the generated amount of water given enough temperature differentials. Understanding this transport process is necessary to properly engineer the water balance in the fuel cell to ensure high performance and long operational life. Channel-land architecture, diffusion media heat and mass transport properties, and operational age can all have an influence on thermally driven flow. High resolution neutron imaging was used to determine the steady-state water accumulation in various cell configurations to understand the influence of these ...